Iodine is used by the thyroid to produce thyroid hormones and is actually used by other tissue as well. Only 80% of iodine is found in the thyroid, whereas the other 20% are found in other tissue such as salivary glands, gastric mucosa, the choroid plexus (brain), ciliary body of the eye, lacrimal gland, thymus, skin, placenta, prostate, and pancreas…
Oceans are the main source, where the soil contains very little. Foods that grow close to the sea contains more iodine, due to the sea winds that bring iodine to the soil. Seaweeds such as wakame, nori or mekabu, contains significant amounts of iodine.
The thyroid manufactures thyroid hormones in the gland from one molecule of the amino acid tyrosine and iodine—four iodine atoms per tyrosine molecule in the case of thyroxine (T4), and three iodine atoms in the case of triiodothyronine (T3).
99% of all thyroid hormones are bound to proteins, while only 1% is free in serum. 80% of T3 is deiodinated from T4, to be used by tissue. T4 crosses the blood-brain barrier better than T3, so he brain requires more T4 as it can convert it to T3. A decrease in T4 results in an increase in thyroid stimulating hormone (TSH) which signals the thyroid to produce more thyroid hormones. TSH also increases the conversion of T4 to T3.
Major effects of thyroid hormones:
- Regulates basal metabolic rate
- Regulates nutrient metabolism (digestion, absorption, transport, insulin sensitivity etc…)
- Regulates on ion transport/muscle contraction
- Development, growth (height and muscle size), and steroidogenesis
Being more active and healthy, with a fast metabolism and high testosterone production demands more thyroid hormones, specifically T3.
Many other nutrients are important for optimal thyroid function as well as the conversion of T4 to T3. Few of these nutrients include vitamin A, selenium, vitamin D, zinc, magnesium, vitamin B6, and more.
About 120mcg of iodine is sufficient for thyroid hormone production. (3) But it’s just the very bare minimum requirement, same as with the minimum vitamin D requirement to prevent rickets.
As toxins, halogens, inflammation, infection increase, so does the need for iodine and it’s cofactors.
Same goes for increased physical activity, steroidogenesis, metabolism all require more thyroid hormone to function more effectively.
Once the thyroid is saturated with iodine (which requires much more than just the RDA of 150mcg to saturate), it further detoxes, replaces and protects the thyroid from radioactive elements as well as toxic halogens which can interfere with thyroid hormone production, such as chlorine, fluoride, bromine and heavy metals such as mercury, lead, aluminium, copper etc (4, 5).
Powerful protective and restorative benefits
Iodine is one of the best free radical scavengers and immune system supporters. It neutralizes and breaks down hydrogen peroxide to form water, preventing the formation of a hydroxyl radical. I2 exerts a 10- or 50-fold greater antioxidant action than ascorbic acid or KI (potassium iodide), respectively.
Iodine also suppresses the levels of pro-inflammatory messengers such as nitric oxide, prostaglandin-E2 (which increases estrogen as well), and proinflammatory cytokines (tumor necrosis factor-α, interleukin-6, and interleukin-1β), making iodine a very effective anti-inflammatory mineral. (6)
Iodine has shown to exert powerful antiproliferative action (prevent the spread of cancerous and tumor) via PPARγ receptor activation. Iodine also protects healthy cells against apoptosis (cell death) and induce apoptosis on cancerous cells. (7)
Iodine has also been used to treat asthma, parasites, syphilis, cancer, Graves’ disease, periodontal disease, and arteriosclerosis.
As iodine has been found in the mucus of the stomach, it protects against incoming toxins and also against abnormal growth of bacteria in the stomach, keeping the gut sterile, clean, healthy and protected. Iodine could thus also be a potent agent against the progression of leaky gut.
Seaweeds and other iodine-rich plants have been used 4 century BC by Theophrastus, Aristotle’s pupil, to treat wounds, such as from sunburns, and its probably also been used before that by others for wounds/infections.
Iodine acts as an Adaptogen
Animal studies have proven that iodine normalizes elevated adrenal corticosteroid hormone secretion related to stress, so it acts as an adaptogen. (8)
Iodine is essential for Testosterone synthesis
Iodine reverses the effects of hypothyroidism on the testicles. Thyroid hormones increase testosterone synthesis, and inadequate T3 will lead to low testosterone and testosterone receptor sensitivity. (9, 10)
Iodine will protect the testes and testosterone from free radicals and oxidative stress, however, when there too way too much iodine in the testes, without enough cofactors, it can actually increase reactive oxygen species (free radicals) and lower testosterone via down-regulation of varies enzymes.
Iodine also binds/interacts with nucleus/steroid receptors and helps to increase receptor sensitivity of T and DHT. (11)
Iodine administration is also able to regenerate damaged Leydig cells (cells in testes where testosterone is made). (12)
Not only does iodine protect the thyroid against toxins such as bromine, fluoride, chlorine, etc, but also all other tissue including testes. If toxins and heavy metals are present in testes, proper testosterone synthesis cannot occur.
Iodine potently lowers Estrogen
Iodine is potentially anti-estrogenic. As seen in this study, treatment with iodine and iodide increases the mRNA levels (increase the expression and activity) of Cytochrome P450 1A1 (CYP1A1) and 1B1 (CYP1B1). These two enzymes are phase I estrogen metabolizing enzymes that oxidize 17β-estradiol (which is carcinogenic) to 2-hydoxyestradiol (2-OH-E2) and 4-hydoxyestradiol (4-OH-E2), respectively. Higher activity of these enzymes leads to greater catabolism of estrogen and urinary excretion of the metabolites.
Iodine also decreases the levels of the estrogen-responsive genes TFF1 and WISP2.
Iodine increases peroxidase activity, which is inversely related to estrogen receptor alpha (ER) concentration, thus restricting estrogen’s action. 2-5mg/day of iodine (I2) diminished translocation of the estrogen receptor alpha. (13, 14, 15)
Iodine treatment increases the catabolism of estrogen and decreases estrogen receptors and estrogen responsiveness to receptors.
Furthermore, iodine saturates as well as inhibit the lipid peroxidation of polyunsaturated fatty acids, preventing its endocrine and metabolism disrupting actions to a great degree.
I advise to stay away from iodated salt and get your iodine from food sources and from supplements containing only organic iodine, not combined with inorganic iodine.
Weston Price reported that the intake of iodine was 131-175 mcg for the Inuit (about the level of the DRI) and 25-34 mcg for Canadian Indians (considered very low, although they did not exhibit thyroid problems). The traditional food of Japanese contains significant amounts of dietary iodine, and they possibly consume at least 7000 mcg of iodine daily from kombu alone (16) with no suppressive effect on the thyroid.
Liquid iodine is clean iodine with a mix of organic and inorganic iodine. Kelp/seaweeds contains just organic iodine as well as many other rare essential trace minerals that your body also needs. I would be much harder, if not impossible, to overdose on iodine from kelp. I don’t think it’s necessary to take more than 1mg daily unless you need to flush out other metals that are interfering with your thyroid or when you want to lower excessive estrogen. Under those circumstances, you could increase your dosage until you see the symptoms diminish and you have found your sweet spot.